ASTRO comes with a short precedure named astro-site.astro, located in the pro directory of your GILDAS installation. This file is executed at the beginning of each ASTRO session, and is used to set default values for the time and observatory parameters.
! ! Observatory and time initialization ! astro\set dut1 -0.3 ! November 2007 Bulletin D 98 of IERS astro\set dtdt 65.184 ! January 2006 Bulletin C 30 of IERS ! astro\observatory ! Select default observatory astro\time ! Use current system time ! if (observatory.eq."BURE") then astro\set azimuth south astro\catalog gag_data:phase-pdb sic\message i site "Plateau de Bure defaults selected" else if (observatory.eq."PICOVELETA") then astro\set azimuth north sic\message i site "Pico Veleta defaults selected" else sic\message i site "No known defaults for this observatory" endif
Note the SET AZIMUTH NORTH|SOUTH command, which is used to define the azimuth to be zero in the North or South directions, to conform to local conventions.